Preheat oven to 350°F. Butter a 9-inch springform pan and line bottom with parchment paper.

Bring about 2-inches of water to a simmer in the bottom half of a double boiler or in a medium saucepan. Place the top half of the double boiler, or a metal bowl or heatproof pan if not using a double boiler, over the simmering water and melt together the chocolate and the 1/4 cup butter. Set aside to cool.

Using a blender, chop the pecans finely. Add the eggs, vanilla, sugar, salt and melted chocolate mixture, blending until smooth. Pour the batter into the buttered springform pan and bake until a toothpick inserted in center comes out moist but not wet, about 40 minutes.

Once it has cooled a little, run the tip of a knife around the pan and release the cake from the pan. Invert onto a plate, and then again, or serve directly onto plates if left on bottom part of springform pan. If desired, sprinkle with confectioners’ sugar and serve with whipped cream and berries.

In a medium saucepan, set over medium heat, add the sugar, water, vanilla and pecans. Stir with a wooden spoon or spatula, occasionally, as it heats. It will come to a simmer, continue to cook for about 6 to 8 minutes. The pecans will be entirely covered by the transparent liquid and there will be a strong simmer.

Suddenly, the mixture will appear as if completely covered in sand: grainy and you will think you have messed it up! You have not. Continue to cook, and that clumped up sugar will begin to melt and caramelize around the already hardened and covered pecans. Stir continuously and don’t let the pecans burn. Adjust the heat if need be. You should continue until you see no more white sugar, and it is all melted and caramel covered, about 10 minutes more.

Pour the mixture onto parchment paper. Separate the pecans as you do, using a wooden spoon, or help yourself with another wooden spoon, using them as extensions of your hands. The caramel dries fast, and you will want to have the individual hardened pecans, not many clumped up. Tough, nothing happens if a few clump up...

Once they have completely cooled and dried, you can store them at room temperature in a tight container.

In a double boiler or water bath, melt the butter with the chocolate, stirring occasionally until completely mixed.

In a small cup, combine the instant coffee with the coffee liquor or water, stir until almost dissolved and pour into the chocolate mixture, it will finish dissolving in the melted chocolate. Mix with a spatula and remove from the heat. Let cool.

In a medium mixing bowl, beat the eggs with a fork or whisk until they have gained some volume and seem foamy. Add the sour cream, vanilla and sugar. Mix with a spatula until thoroughly combined.

In a large mixing bowl, combine the all-purpose flour, baking powder and salt. Stir.

Slowly pour the chocolate mix into egg mixture, mixing with a spatula as you do, until completely combined. Pour that mixture into the dry ingredients and mix until thoroughly combined. Finally, toss in the caramelized pecans and gently fold. Pour into the prepared baking dish and place in the oven. Bake for 20 minutes or until the top has lightly crisped, and the brownies are still moist but not wet (test with a toothpick).

Remove from the oven, let cool and slice into squares. Sprinkle with confectioners’ sugar, if desired.

To make the crust: In a large bowl combine the ground cookies and melted butter until thoroughly mixed. Turn the cookie mixture into the springform pan. With your fingers, pat it evenly around the bottom of the pan, gently pushing it up the sides to make a crust 1/2- to 1-inch tall. Refrigerate while you make the cream cheese filling and dulce de leche topping.

To make cream cheese filling: Place the cream cheese in the bowl of an electric mixer and beat at medium speed until smooth and light, 3 to 4 minutes. Add the sweetened condensed milk and continue beating until well mixed, scraping down the bowl as needed. Add the eggs one at a time, again scraping down the bowl as needed, and continue beating until the mixture is well blended and smooth, set aside.

To make the dulce de leche topping: In a medium bowl, mix the sour cream with the dulce de leche until combined.

Adjust the oven rack to the lower third of the oven and preheat to 350°F.

Remove the springform pan from the refrigerator. Gently spread the cream cheese filling evenly, trying not to distress the crust. Place the cheesecake in the oven and bake for 35 minutes, or until it is set and the top is lightly browned. Remove from the oven and let cool for at least 10 minutes before you add the dulce de leche topping.

Spoon the dulce de leche topping over the cream cheese filling, add the pecans all around the edge and place the pan back in the oven for 10 more minutes. Remove from the oven and let the cheesecake cool to room temperature. Cover and refrigerate for at least 4 hours before serving. It tastes even better if it chills overnight.

Before serving, run the tip of a wet knife around the edge of the pan to release the cheesecake. Remove the ring, then slice and serve the cake.